1. Field of the Invention
The present invention relates to a paper discharge device for conveying paper from an input side to a discharge port and, more specifically, to a paper discharge device for use in a conveyance device of a printer for conveying paper, such as a receipt or a ticket, after a printing operation.
2. Description of the Related Art
A paper discharge device for conveying paper to a discharge port to discharge the paper is provided in a thermal printer of a cash register, a ticket issuing machine for printing and then issuing a ticket, or the like.
In a cash register, a ticket issuing machine, or the like, when a leading end of paper protrudes from the discharge port when the paper is discharged, there is a fear that a situation may occur where the paper is pulled or sandwiched to be held outside the machine before the paper is completely discharged.
If the paper is pulled or held before the paper is completely discharged, unnecessary tension or stress is applied from the paper discharge device to the paper in a printing device or a paper cutting device at the previous stage to cause inconvenience such as degradation of the printing quality and irregular cut portions. Further, since stress is applied to the paper, jamming may be caused in the printing device or the paper cutting device.
In order to prevent such inconvenience, conventionally, a paper discharge device is devised which is adapted to stock paper until a printing process and a cutting process are completed and to discharge the paper after the printing process and the cutting process are completed, such as a paper conveyance device 160 disclosed in Japanese Patent No. 2721112 shown in FIG. 7.
In the paper conveyance device 160, a stock space 164 for stocking paper is provided between an input port 165 which is provided on an input side of the paper where the paper is input and conveyance rollers 161 and 162 for conveying the paper. After the leading end of the paper 60 fed from the input port 165 is sandwiched between the conveyance rollers 161 and 162, the conveyance rollers 161 and 162 are stopped while the paper 60 is continued to be conveyed from devices at the previous stage (a printing device 171 and a cutting device 172). This allows the paper 60 to be temporarily bent in the stock space 164. After the printing process and the cutting process are completed, the conveyance rollers 161 and 162 are driven to discharge the paper from a discharge port 166.
However, in the paper conveyance device according to the above patent, as mentioned in the patent itself, it is not so easy to successfully bend the paper 60 in the device. For example, the paper 60 is not successfully bent unless the angle formed between the conveyance rollers 161 and 162 and a conveyance path of the paper 60 is appropriate. Further, in order to bend the paper 60, it is necessary to, after the conveyance rollers 161 and 162 sandwich the paper 60, rotate the conveyance rollers 161 and 162 in the reverse direction by a very small amount to apply stress to the paper 60. The paper 60 can not be bent successfully without the reverse rotation.
In a paper discharge device structured to stock paper by bending the paper, if the paper can not be bent successfully, various kinds of inconvenience are caused such as a longitudinal wrinkle or fold due to unnatural stress acting on the paper and jamming due to unnatural stress traveling to the paper in the printing device or the cutting device.
Further, a paper discharge device structured to stock paper by bending the paper also has a problem in that it has low adaptability to the kind of the paper and can not accommodate, for example, thick paper, sturdy paper, and plastic paper.
As another paper discharge device adapted to stock paper in the device until the printing process and the cutting process of paper are completed, a paper discharge device adapted to stack paper in a paper conveyance path from a cutting device to a discharge port which is lengthened by detouring or the like is devised. Such a device has, however, a problem in that, since the length of paper which can be stocked is the same as the length of the conveyance path, it is constant, and, in case paper the length of which is longer is fed, the leading end of the paper protrudes before the process by the devices at the previous stage is completed.
Further, Japanese Patent No. 2893663 discloses a conveyance direction changeover device for a sheet-like article for reversing the direction of feeding the sheet-like article on the way in a conveyance path. In this conveyance direction changeover device, a pair of conveyance rollers are provided ahead of an input path. A second conveyance path is provided on the opposite side of the input path with the pair of the conveyance rollers sandwiched therebetween, while a first conveyance path is provided on the side of the input path so as to be a branch from the input path. A sheet-like article fed from the input path is once fed to the second conveyance path by the pair of the conveyance rollers. When the trailing end of the sheet-like article reaches the position of the pair of the conveyance rollers and while the trailing end of the sheet-like article is still sandwiched between the pair of the conveyance rollers, the direction of feeding the sheet-like article is reversed to make the sheet-like article go to the side of the first conveyance path branching from the input path. In this way, the direction of conveyance of the sheet-like article is reversed.
However, the above conveyance direction changeover device is not a device for discharging paper or the like to the exterior but a device for changing over the direction of conveyance of the sheet-like article in the process of performing various kinds of processing in the device, and thus, does not fall within the scope of the present invention.
Further, for the purpose of changing the direction of a sheet-like article from the side of the input path to the side of the first conveyance path, the above conveyance direction changeover device adopts the following structure. While the input path is provided such that the sheet-like article goes to a direction diagonal with respect to the pair of the conveyance rollers (to a direction tilted from a perpendicular to a line connecting central points of the pair of the conveyance rollers), the first conveyance path is provided such that the sheet-like article goes straight from the pair of the conveyance rollers (to a perpendicular direction to the line connecting the central points of the pair of the conveyance rollers).
However, though the above structure can accommodate sturdy and straight paper without a problem, in case paper having peculiarities or paper which is not sturdy is used, there is a fear that the paper sandwiched between the pair of the conveyance rollers may not extend straight and may be deflected due to the peculiarities or unsturdiness, and the paper does not go successfully to the side of the first conveyance path.
An object of the present invention is to provide a paper discharge device which can temporarily stock paper without wrinkling or folding the paper until processing such as printing or cutting at the previous stage is completed and discharge the paper from a discharge port after the processing is completed, without a limitation on the kind and length of paper used.
In order to attain the above object, according to the present invention, a paper discharge device has a driving roller, a driven roller in contact with and following the driving roller, and rotational drive means for rotating the driving roller, the paper being sandwiched between the driving roller and the driven roller and conveyed from an input side to a discharge port. The paper discharge device has a first conveyance path for guiding the paper from the input side to between the driving roller and the driven roller, a second conveyance path having an initiating end joined to the first conveyance path at a point nearer to the input side than a point where the driving roller and the driven roller come in contact and a terminating end connected to the discharge port, a paper stock space provided on a side opposite to the input side with the contact point of the driving roller and the driven roller being sandwiched therebetween a third conveyance path for guiding the paper from the contact point of the driving roller and the driven roller to the paper stock space, and control means for controlling the rotational drive means such that the paper inputted from the input side along the first conveyance path is conveyed by the driving roller and the driven roller to a side of the paper stock space and, after a trailing end of the paper passes the joining point of the first conveyance path and the second conveyance path, the paper feed direction by the driving roller is reversed to feed the paper along the second conveyance path to the discharge port.
Such means makes it possible to feed the paper inputted from the input side to a forward direction by the driving roller to guide the paper to the paper stock space, and, after the trailing end of the paper passes the joining point of the first conveyance path and the second conveyance path, the paper feed direction by the driving roller is reversed to guide the trailing end of the paper to the second conveyance path and then feed the paper to the discharge port.
In such a conveyance method, since the paper can be stocked in the paper stock space, the paper is not discharged from the discharge port until the processing by devices at the previous stage (such as printing or cutting) is completed, and can be discharged from the discharge port to the external after the processing by the devices at the previous stage is completed.
Further, since the method of stocking the paper is just feeding the paper in the forward direction and allowing the paper to droop due to its own weight in the paper stock space, no difficult control is necessary to stock the paper. Further, since no particular stress or tension is necessary to be applied to the paper, there is no fear that the paper is wrinkled or folded, and various kinds of paper such as thick paper, sturdy paper, and plastic paper, and various paper lengths can be accommodated.
Here, the above series of conveyance control can be performed by a controller for controlling the whole apparatus such as a printer, or alternatively, a dedicated controller for the paper discharge device may be provided to perform the control.
Preferably, guide means is provided at the joining point of the first conveyance path and the second conveyance path for preventing the paper fed in the reverse direction from flowing in the first conveyance path and for guiding the paper to the side of the second conveyance path.
Such guide means can prevent a mistake that, for example, when the paper is fed in the reverse direction, the trailing end of the paper goes not to the side of the second conveyance path but to the side of the first conveyance path, even if the paper has strong peculiarities or the paper is not sturdy.
More specifically, by providing the guide means of a cantilevered resilient guide piece (for example, a thin plastic piece), an end thereof being in contact with either the driving roller or the driven roller, when the paper is fed along the first conveyance path to between the driving roller and the driven roller, the guide piece can be deformed to allow the paper to pass while, when the paper is fed through the joining point of the first conveyance path and the second conveyance path in the reverse direction, the guide piece can shut out access to the side of the first conveyance path and can guide the paper to the side of the second conveyance path.
More preferably, first detection means for detecting whether there is the paper or not is provided near the joining point of the first conveyance path and the second conveyance path, and the control means changes over the operation of the rotational drive means based on the result of detection of the first detection means.
Such a structure makes it possible to recognize with accuracy that the trailing end of the paper has passed the joining point of the first conveyance path and the second conveyance path and the paper feed direction can now be reversed. Therefore, a mistake can be prevented from happening that, for example, when the trailing end of the paper is guided to the side of the second conveyance path, the trailing end of the paper is still on the side of the first conveyance path and can not be successfully guided to the side of the second conveyance path.
Further, preferably, second detection means for detecting whether there is the paper or not is provided near the contact point of the driving roller and the driven roller, and the control means changes over the operation of the rotational drive means based on the result of detection of the first detection means and the second detection means.
After the trailing end of the paper passes the contact point of the driving roller and the driven roller, since the paper leaves the conveyance mechanism, the paper can not be conveyed in the reverse direction by rotating the driving roller and the driven roller in the reverse direction. Therefore, the timing when the paper is fed in the reverse direction in order to guide the paper to the second conveyance path has to be timing after the trailing end of the paper passes the joining point of the first conveyance path and the second conveyance path and when the paper remains between the driving roller and the driven roller. The above means makes it possible to recognize with accuracy the state where the paper remains between the driving roller and the driven roller by the detection by the second detection means.
Further, a collection space for stocking the paper after a trailing end thereof passes between the rollers is provided ahead of the third conveyance path, and the control means controls the rotational drive means based on a preset condition and conveys the paper left in the second conveyance path through the third conveyance path and the paper stock space to the collection space.
Such a structure makes it possible that, in case discharged paper is not taken out and remains in a protruding state from the discharge port and predetermined time elapses, the paper is drawn from the discharge port back to the inside of the device to be collected in the collection space.
Further, preferably, the paper stock space is formed to allow the leading end of the paper conveyed by the driving roller and the driven roller to droop due to its own weight. By this, the paper can be stocked naturally.